Washington (CNN) -- An vehicle carrying U.S. Embassy personnel in Yemen was attacked this week, but nobody was injured, the State Department said Thursday.

The bomb attack on an embassy vehicle occurred Wednesday in a suburb of the capital, Sanaa, State Department spokesman P.J. Crowley said. The car was parked "in front of a restaurant frequented by Westerners," he said.

"We can confirm that four American embassy personnel were in the vehicle and no one was injured," the spokesman said. "We have no further information for you at this time, as an investigation is currently under way."

It wasn't clear if the four people in the car were Americans. Crowley said the bomb went off outside the vehicle.

A Yemeni official confirmed the attack, which happened in the Hadda district, where many foreigners live, in an area where many restaurants are located.

The official said a suspect is in custody, describing him as a "foreign national." The suspect was found in illegal possession of a weapon and had "many fraudulent documents," the official said.

Assistant Secretary of State Jeffrey Feltman, who was in Yemen earlier that day, had already departed for Libya, Crowley said.

A "warden's message" posted for U.S. citizens in Yemen says, "On December 15, 2010 foreign residents in Sanaa, Yemen, were targeted for attack. The U.S. Embassy urges U.S. citizens to remain vigilant regarding their personal security and to avoid areas where this and similar attacks have occurred."

The State Department's most recent travel advisory for Yemen warns Americans of threats to U.S. interests due to active terrorist activity, specifically from al Qaeda in the Arabian Peninsula. Embassy employees in Sanaa are instructed to use caution when visiting restaurants, hotels or tourist areas in the capital and are forbidden from traveling outside the capital.

The U.S. Embassy in Sanaa has closed in the past amid ongoing threats against U.S. interests in the country. In September 2008, armed extremists attacked the embassy, killing a security guard, several Yemeni security personnel and innocent civilians outside the embassy, including a U.S. citizen.

In October the motorcade of the British deputy ambassador was attacked and in April the British ambassador's car was the target of a failed bomb attack.